Cellulose derivative compositions



Dec. 26, 1961 F. P. NYBERG 3,014,808

CELLULOSE DERIVATIVE COMPOSITIONS Filed Feb. 2, 1959 V 2 Sheets-Sheet 1F ig .1

Viscosity of mixtures of ethyl hydroxyeth' lcelluloses and mixtures ofcurboxyme hylcelluloses Corboxymethylcellulose Viscosity, cP

Ethyl-hydraxyethylcelLulose l l l l U Bor D 10D 80 60 4U 20 0% Aor CINVENTOR ke Pe'hus N /er m msmvzuxw ATTORNEYS Dec. 26, 1961 F. P. NYBERG3, 4,8

CELLULOSE DERIVATIVE COMPOSITIONS Filed Feb. 2, 1959 2 SheetsSheet 2Fig.2

Viscosity of mixtures of ethylhydroxyethylcellulose ondcorboxymethylcellulose Viscosity, cP

Ethylhydroxyethyl' cellulose 100 80 60 L 0 0 20 40Curboxymethylcellulose INVENTOR -glik/w Wave/yew ATTORNEY$ Patented Dec.26, 1961 [ice 3,014,808 CELLULOSE DERIVATIVE COMPOSTHQNS Folke EetrusNyberg, Ornskolldsvik, Sweden, assignor to M och Domsjti Aktiebolag,Ornskoldsvik, Sweden, a corporation of Sweden Filed Feb. 2, 1959, Ser.No. 790,627 Claims priority, application Sweden, Feb. 21, 1958 3 Ciaims.(Ci. Did-197) The present invention relates to cellulose derivativecompositions useful as adhesives, thickening agents and the like, and ismore particularly concerned with a cellulose derivative compositioncomprising a water-soluble ethyl-hydroxyethylcellulose and awater-soluble ionic cellulose derivative, said two ingredients beingpresent in proportions within the range of 5 to 95% by weight of one ofthem and correspondingly 95 to 5% by weight of the other, based on thesum of these two ingredients.

Many cellulose derivatives have found extensive use as adhesives,thickening agents, dispersing agents and the like for a variety ofindustrial purposes. Examples of such uses include base materials incosmetic and pharmaceutical ointments and salves, bonding agents intablets, thickening and stabilizing agents in foodstuffs, thickeningagents in shoe colors, thickening and dispersing agents in detergentcompositions, emulsifiers and binding agents in insecticidal and similarcompositions, additives to coating compositions, impregnatingcompositions and sizes for paper, adhesives for paperboard and paper,warp sizes, thickening agents in emulsion paints and filling putties,foundry core binders and adhesives, wall-paper pastes etc. in many suchapplications it is desirable, on dissolving the cellulose derivative inwater to obtain a solution exhibiting a high viscosity at a low contentof cellulose derivative or in other words to obtain the highest possiblethickening effect at a given concentration of the thickening agent. Thiseffect is usually achieved by using a cellulose derivative of a highmolecular weight for which purpose it is necessary to see to it thatdegradation of the cellulose during preparation of the cellulosederivative is minimized.

The viscosity of a mixture of two water-soluble cellulose derivatives ofdifferent viscosities, e.g. two different ethyl-hydroxyethylcellulose ortwo different carboxymethylcelluloses, can readily be calculated fromthe known viscosities of the ingredients (at a certain givenconcentration). In a graph where the logarithm of the viscosity (log'17) is plotted against the percentage composition of the mixtures, thelogarithm of the viscosity of a mixture will be close to the straightline connecting log 1 for each of the two components. Of course, thetotal concentration of the solutions is presumed to be constant.

It was surprisingly found that a mixture of ethyl-hydroxyethylcelluloseand at least one anionic cellulose derivative, when dissolved in water,has a viscosity which is substantially above the viscosity which couldbe expected on the basis of the viscosities of the two components inaccordance with the rule explained above. As long as the viscosities ofthe two components are not too different the viscosity will even oftenbe substantially above the viscosity of the most viscous of the twocomponents.

Water-soluble ionic cellulose derivatives to be used in the compositionof this invention include e.g. watersoluble types ofcarboxymethylcellulose, carboxyethylcellulose, sulfomethylcellulose,sulfoethylcellulose and cellulose sulfate, including water-soluble saltsof these cellulose derivatives.

The above-mentioned water-soluble cellulose derivatives are known perse. The solubility characteristics of cellulosederivatives of thesetypes depend, as in the case of cellulose derivatives generally, onseveral factors and among them primarily on the degree of substitution,i.e. the average number of substituent groups per anhydroglucose unit inthe cellulose molecule. As a general rule, a low degree of substitutionresults in solubility in aqueous alkali only, and a higher degree ofsubstitution gives solubility in both aqueous alkali and water. Forcellulose ethers containing for example ethyl groups it is also to benoted that the solubility in water is reduced on further increase of thedegree of substitution above a certain optimum value, due to the factthat ethyl groups are of a hydrophobic nature in themselves. However,the solubility depends not only on the degree of substitution, but alsoon the average degree of polymerization or average molecular weight ofthe cellulose derivative in that the solubility increases somewhat withdecreasing degree of polymerization. Another factor which largelyinfluences the solubility characteristics of cellulose derivatives,consists in the conditions of reaction under which the cellulosederivative in question is prepared. The manner in which the reactionconditions affect the solubility is that if they are such as to favor auniform substitution, i.e. the substituent groups are uniformlydistributed along the cellulose molecule chain, solubility in water willbe obtained at a degree of substitution which is lower than that atwhich solubility is obtained with a non-uniform substitution. On accountof these circumstances it is impossible to specify definite limits forthe degree of substitution within which solubility in water is obtained.The maximum degree of substitution for the cellulose derivativescontemplated here is 3.0 except in the case of the hydroxyethyl groupthe degree of substitution of which is unlimited (since it contains ahydroxyl group which can be etherified by another hydroxyethyl groupetc. to form ethyleneoxy ether chains). As regards such Water-solublecellulose derivatives of the types contemplated here, which areavailable in practice, it can be mentioned, however, that the degree ofsubstitution generally lies within the following ranges:Ethyl-hydroxyethylcellulose 0.2 to 2.0 as regards ethyl and 0.2 to 2.0as regards hydroxyethyl groups; carboxymethylcellulose 0.4 to 1.5;sulfomethylcellulose 0.1 to 1.0; sulfoethylcellulose 0.4 to 1.5;cellulose sulfate 0.1 to 1.0. For carboxyethylcellulose it is reportedthat solubility in water requires the use of at least 1 molecule ofetherification agent per anhydroglucose unit. However, since thesewater-soluble cellulose derivatives and methods for their preparationare wellknown to those skilled in the art and described in theliterature, it is not considered necessary to specify the degree ofsubstitution for the purposes of this invention.

The increase in viscosity will generally be noticeable already when arather small proportion of one component is admixed to the other. Toachieve an increase in viscosity suflicient for practical purposes,however, both components should be present in proportions of at least 5%based on the weight of the mixture, i.e. the mixing ratio by weight ofethyl-hydroxyethylcellulose to the ionic cellulose derivative rangesfrom 5/95 to 95/5. Preferably mixing ratios within the range of /20 to20/80,by weight, will be employed.

Of course, compositions within the scope of this invention may containothe arbitrary additions. It will be noted that the percentages statedabove and in the appended claims relate only to the cellulose derivativecomponents and that any other substances added are not included.

The invention is illustrated by the examplesset forth below and theaccompanying drawings, wherein FiGURE 1 is a graph ilustrating theviscosities of various mixtures of two ethyi-hydroxyethylcellul se.-s ofdifferent vis cosities as well as those of various mixtures of twocarboxyrnethylcelluloses of different viscositics, and FIG- URE 2 is agraph illustrating theviscosities of various mixtures of anethyl-hydroxyethylcellulose and a carboxy- The results are also setforth graphically in FIGURE 1 methylcellulose. where the viscosityvalues are plotted on a logarithmic In the examples below as well as onthe drawings, the scale against the percentage compositions of themixterm viscosity means the viscosity measured at 20 C. tures. It isseen that the viscosities of the various mixmeasured with a Brookfieldviscometer one day after 5 tures correspond well to those which can becalculated preparation of the solution. When nothing else is stated, inaccordance with the rule explained above, i.c. the viscosity in a 2%solution is intended. All percentages logarithms of the viscosities ofthe mixtures lie close to are by weight. the straight line connectinglog '2 of the two components EXAMPLE 1 of the mixtures.

This example is intended to show the viscosity values EXAMPLE 2 obtainedby mixing two cellulose derivatives which are A hiohwiscosityethyphydmxyethylceuulose having a similar 1n structure but havedifferent viscosities and illusviscosit; of 7715 and containing 13 0% fethoxyl trates the rule explained hereinbefore for calculating the and160% of ethylene Oxide (corresimnciing to a degree Vlscoslty of themixture- In these experiments two difler' 15 of substitution of 0.88 forethoxyl and 0.82 for ethylene ent ethyl-hydroxyethylcelluloses and twodiiferent caroxide) and a Salt content f of 01 was mixedboxymethylcelluloses were used. These had the followin varyingproportions with a highwiscosiiy Carboxymg charactenstlcsmethylcellulose(sodium salt) of the viscosity S940 cp.,

degree of substitution 0.47 and salt content 4.7% of (A)Ethyl-11ydroxyethylcellulose. 0 NaCl. The viscosities of the mixtureswere determined.

Viscosity-240 cp. Chemical composition The results are set forth inTable II below.

15.7% of ethoxyl (OC H 13.5% of ethylene oxide (OC H Table 11 Saltcontent-0.4% of NaCl (B) Ethyl-hydroxyethylcellulose: Proportionsolethyl- Proportions ofethyl- Vi i 184O Cp hydroxfiethylcelilulloseViscosity, hydroxyfthylcelllullose Viscosity,

to car orvmct y cp. to car oxylnet y ep. Chemical composrtroncellulosecellulose 17.0% of ethoxyl 12.4% of ethylene oxide 14,330 Saltcontent-4.2% of NaCl 13238 (C) Carboxymethylcellulose (Na salt): 8:320Viscosity-580 op. Degree of substitution0.66 Salt content6.8% of NaCl(D) izgg gj i g i (Na salt) These values are plotted in FIGURE 2 in thesame Degree of substitliiion-0 66 t as in is apparent that the ga- Saltcontsnpq 2% of rlthms of the mixture vlscosltles are alwayssubstantlally above the straight line connecting log 1 of the two com-The products A and B and the products C and D were 40 ponems mixed invarying proportions, and determinations of vis- EXAMPLE 3 cosities werecarried out on the mixtures. The results A low-viscosityethyl-hydroxyethylcellulose (viscosity are set forth in Table I below.439 cp.; 15.7% ethoxyl, 13.5% ethylene oxide; salt con- Table I tent0.4% NaCl) was mixed with an equal amount of low-viscositycarboxymethylcellulose (viscosity 463 cp.; degree of substitution 1.1;salt content 0.3% NaCl). vlscoslty'cp' A 1% aqueous solution of thismixture exhibited a viscosity of 99 cp. The corresponding values of 1%Mlxmg proportions (ED and 02D resp') aqueous solutions of theethyl-hydroxyethylcellulose and ceAllulgse fi the carboxymethylcelluloseare 46 cp. and 101 cp. respectively. On the basis of these values theviscosity of a 1% solution of the mixture, calculated in accordance withthe rule explained hereinbefore, would be 68 cp.

EXAMPLES 4 TO 7 Various ethyl-hydroxyethylcelluloses were mixed withvarious ionic cellulose derivatives in 50:50 proportions. Thecharacteristics of the products, the viscosities of the mixtures and theviscosities which should be expected on the basis of the above rule areset forth in Table III.

Table III Ethjbhydroxyethylcellulose Ionic cellulose derivative FoundCalcu- Substitution viscosity latct l Ex. V Salt, Salt, of mix- V1?"0Slty iscosity percent Product Viscosity, Substipercent, turc cp. 0 ml:-

cp. Ethoxyl 5332 NaCl up. tution NaCl turn, cp.

percent 224 18. 4 13.4 2. 5 Carboxymethyl cellulose (Na salt) 463 1.10.3 495 2 1,340 29.4 8.9 0.3 do 1,175 0.55 4.2 2, 1,240 116 18. 4 13. 42. 7 Cellulose sulfat (Na salt) 6.3% s 14% ash 134 113 439 18. 4 13. 43. 2 Sulfornethyl cellulose (Na sal 512 0. 25 696 4 5 I claim:

1. A cellulose derivative composition comprising 5-95% by weight of (1)a water-soluble ethylhydroxyethylcellulose and correspondingly 955% byweight of (2) at least one water-soluble ionic cellulose derivative.

2. A composition as claimed in claim 1 comprising 20-80% by weight ofcomponent (1) and correspondingly 8020% by Weight of component (2).

3. A composition as claimed in claim 1 in which component (2) isselected from the class consisting of watersoluble salts ofcarboxymethylcellulose, carboxyethylcellulose, sulfomethylcellulose,sulfoethylcellulose and cellulose sulfate.

References Cited in the file of this patent UNITED STATES PATENTS OTHERREFERENCES Modocoll: MO OCH Domsjo AB Pamphlet, July 1952. Ott et al.:High Polymers, vol. 4(Cellu1ose), 2nd ed.,

1955, page 948.

1. A CELLULOSE DERIVATIVE COMPOSITION COMPRISING 5-95% BY WEIGHT OF (1)A WATER-SOLUBLE ETHYLHYDROXYETHYLCELLULOSE AND CORRESPONDINGLY 95-5% BYWEIGHT OF (2) AT LEAST ONE WATER-SOLUBLE IONIC CELLULOSE DERIVATIVE.